Abstract
The aims of this study were to characterize variations in LEP exon 3 region in Najdi sheep and assess their associations with milk and udder traits. A PCR amplicon of 471 bp was amplified and sequenced. Aligned DNA sequences showed two non-synonymous single nucleotide polymorphisms. At position G286T, three haplotypes were recovered; GG, TT and GT. For SNP G332A, only two homozygous haplotypes were recovered; GG and AA. The G-bearing genotypes (GG and GT) of G286T had an average of 27.2, 31.2, 28.9 and 21.2% higher values (P<0.05) for daily milk yield, total protein, total lactose and total milk solids than the T allele homozygotes at day 21 of lactation, respectively. At day 84 of lactation, the T allele homozygotes of G286T were significantly (P<0.05) associated with higher milk yield and milk constituents than the G-bearing genotypes (GG and GT); no differences (P>0.05) in milk and udder traits were detected between G allele homozygotes and GT heterozygotes of G286T. For the SNP G332A, genotypes were not significantly associated with daily milk yield, milk constituents and udder traits. It is suggested that different effects of Najdi genotypes on milk yield during suckling and milking periods may be due to differential expression of LEP gene in each period.